SpringCloud implements communication between Microservices through RestTemplate
Maven coordinates of dependent class libraries:
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
<version>2.2.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<version>2.2.2.RELEASE</version>
</dependency>
These dependent class libraries include the Spring Cloud Eureka client and the Spring Boot Web Components.
Spring Cloud Eureka is a solution for service registration and discovery, which can be used to build an application architecture based on Microservices. It provides a service registry where each Microservices can register itself and obtain service information from the center.
Spring Boot is a framework for creating standalone Spring applications, which simplifies the configuration and deployment process of Spring applications.
The following is an example code of using SpringCloud and RestTemplate to achieve communication between Microservices:
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
@SpringBootApplication
public class MicroserviceClientApplication {
public static void main(String[] args) {
SpringApplication.run(MicroserviceClientApplication.class, args);
}
@LoadBalanced
@Bean
public RestTemplate restTemplate() {
return new RestTemplate();
}
@Autowired
private RestTemplate restTemplate;
@RestController
public class ClientController {
@GetMapping("/hello")
public String hello() {
String URL=“ http://microservice-provider/hello //Call the service based on its name
return restTemplate.getForObject(url, String.class);
}
}
}
In the code, we created a bean of 'RestTemplate' in the main class and annotated it with '@ LoadBalanced' to enable 'RestTemplate' to have load balancing capabilities.
In 'ClientController', we define a 'hello' interface that calls the '/hello' interface of the 'microservice provider' service. Among them, 'microservice provider' is the service name of the service provider, and Spring Cloud can discover services based on the service name and forward requests to the actual service instance.
Finally, we use the 'getForObject' method of 'RestTemplate' to initiate an HTTP GET request and return the result as a string.
Summary:
Spring Cloud realizes communication between Microservices through RestTemplate. We can use 'RestTemplate' to initiate HTTP requests and obtain responses, so as to realize data transmission between different services. Through the service discovery mechanism of Spring Cloud, we can use the service name for service discovery and request forwarding to achieve load balancing and highly available Microservices architecture. The above is a simple example that you can adjust and expand according to actual needs.
